You have taken Him, who was handed over to you by the ordained counsel and foreknowledge of God, and by lawless hands have crucified and killed Him, whom God raised up by loosening the pull of death, because it was not possible that He should be held by it.

Acts 2:23–24 — Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)

Given His earthly ministry, Jesus spoke of His death and His resurrection. At best, His disciples were oblivious to the things He said about it. They didn’t understand the resurrection, nor did they expect it. Think about that, imagine someone trying to tell you about hypervisor. It’s real. But most peoples’ collective wisdom knows no such thing. It would be hard to explain any details to anyone who didn’t know what it is. Resurrection would be the same thing. No person who heard Jesus had experienced anybody walking out of a grave after three days dead.

But now they did!

In the citation above, Peter is preaching. Even in the early stages of this ministry, what Peter didn’t know before the crucifixion, He now clearly understood.

There was no possible way death could have power over Jesus. Peter explains it by quoting David.

For David says concerning Him: ‘I foresaw the Lord always before me, for He is at my right hand, that I may not be shaken. Therefore my heart was glad, and my tongue rejoiced; moreover my flesh will dwell in hope. For You will not abandon my soul to Hades, nor will You allow Your Holy One to see corruption. You have made known to me the ways of life; You will make me full of joy with Your presence.’

Acts 2:25–28 — Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)

You will not allow Your Holy One to see corruption.

That’s it. Jesus is that Holy One. Corruption has no power over holiness. Peter continues urgently; he speaks of David having died and been buried. He speaks of the presence of David’s tomb. Yet David knew the promises of God were true, that He would raise up the Messiah to sit on his own throne.

he foresaw this and spoke concerning the resurrection of the Christ, that His soul was not abandoned to Hades, nor did His flesh see corruption. God raised up this Jesus, of which we all are witnesses. Therefore being exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He has poured out this which you now see and hear.

Acts 2:31–33 — Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)

Those present were also privy to the recent events, and now they were eyewitnesses to this pouring out of the Holy Spirit. They see and hear for themselves.

Peter is telling them what David told them, this Messiah would be Lord. That is, the very God of David.

For David has not ascended to the heavens, yet he says:
‘The Lord said to my Lord,
“Sit at My right hand,
Until I make Your enemies
Your footstool.” ’
“Therefore, let all the house of Israel assuredly know that God has made this Jesus, whom you have crucified, both Lord and Christ.”

Acts 2:34–36 — Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)